Many laws govern the transport of certain materials, for example, across government borders. These laws are often enacted to protect the public from exposure to illegal or hazardous materials. In particular, the transport of hazardous materials, such as radiological materials, poses a significant threat to the public. It is, therefore, desirable to detect the presence of certain materials so that action may be taken to prevent potential dangers.
In some cases, certain materials are surreptitiously transported in containers to conceal their presence. Border inspections are often provided to identify illegal and/or hazardous materials. Cargo ships, trucks, and other transport vehicles carry a vast amount of containers into, for example, the United States every day. The vast quantity of containers transported across such borders limit the ability to examine all containers and/or detect certain materials. Moreover, manning, tools and/or facilities are often limited or unavailable for inspection of containers.
Some scanning tools have been employed, for example, at border stations to inspect incoming containers and detect illegal and/or hazardous materials. For example, radiation detectors, such as Geiger counters, have been developed to determine the presence of radiation. More recently, material sensors, such as scintillation detectors (e.g. sodium iodide, cesium iodide, lanthanum bromide detectors), isotope identifiers (e.g. GR-135), neutron counters (e.g. LLNL-developed or other fission meters), spectroscopic tools (e.g. gamma ray detectors) and other equipment, have been developed to sense the presence of radioactive materials. Examples of techniques for material sensing are described in U.S. Pat. Nos. 7,186,987, 7,019,637, 6,649,915, 6,480,141, 6,373,064, 6,344,650, and 6175120.
Material sensors typically need to be placed in proximity to a source to detect material parameters, such as those detected using the scanning tools listed above and/or other measurements, that are indicative of the presence of a specified material therein. Given the vast quantity of materials that are transported daily, such proximate placement for sensing is not always feasible. Moreover, materials are often transported in containers and/or in vessels that can be difficult to access. For example, cargo ships often contain a large number of heavy containers that are lifted by crane and stacked in a cargo hold. The placement and structure of containers may make it challenging for sensors to detect materials housed within the containers. Accessing containers in a storage facility and/or detecting materials in the containers can be difficult and time consuming.
Techniques have been developed and/or suggested to facilitate inspection of containers. Manual devices, such as Geiger counters, have been used by individuals to scan containers. Stationary devices have been developed to place sensors at certain locations to inspect materials as they pass the sensor. For example, suggestions have been made to instrument cargo ships with sensors, or to position sensors in vessel cargo bays, to detect certain materials. Techniques have also been suggested to deploy mobile robots. Some robotic techniques may involve cooperative robotics, tandem robots or robotic swarms. Examples of robotic techniques are described in US Patent/Publication Nos. 20040112238, U.S. Pat. Nos. 6,480,141, 6,438,456, 6,247,546, 6,308,791, 6,687,571, 6,523,629, 6,408,226, 6,484,083, 6,636,847, 6,826,431, and 6,377,878. While various existing detection devices and robotic techniques may be useful in certain applications, efficient inspection of containers, such as incoming cargo, remains a challenge.
Despite the development and advancement of various inspection or robotic devices, there remains a need to provide techniques for efficiently inspecting a group of containers to determine the presence of certain materials. It is desirable that such techniques enable selective positioning of inspectors having sensing capabilities at various locations on, between and/or about the containers as necessary to detect certain materials. It is further desirable that such techniques provide for cooperative inspecting of the group of containers to efficiently complete inspection. Such inspectors would preferably provide one or more of the following features/functions, among others: selective positioning of the inspectors about a group of containers, extendable sensors positionable proximate even remote containers, means for traversing containers or other obstacles to position the inspectors in a known and/or desired position, cooperatively inspecting a group of containers, data processing and/or analysis (locally and/or remotely), and communication (e.g. data and/or commands) between the inspector(s) and/or external sources. Such desired techniques and/or features are not known to exist in the prior art.